142 THE REASON WHY : 



&quot; As for such as are whole-footed, or whose toes are ivebbed 

 together (excepting some few) their legs are generally short, 

 which is the most convenient size for swimming.&quot; DERHAM. 



The ornythorynclius is ahout twenty inches long, having a long and flattened 

 body, like that of the otter, covered with a thick soft fur, moderately dark brown 

 above, and whitish beneath. The beak, like the bill of the duck, is furnished with 

 transverse plates. The teeth are situated in the back of the mouth, two on each 

 side, with flat tops and no roots. The feet are furnished with a membrane uniting 

 the toes, and in the anterior feet extending beyond the nails. The tail is flat and 

 obtuse. From the form of this animal it is fitted to reside in the water ; and it 

 must, feed on soft food, as the structure of the beak will not enable it to grasp 

 anything firmly. The central portion of the mandibles is a bony continuation from 

 the skull, and anterially and laterally, a cartilaginous substance, p.-r: ctly 

 movcable, extends some little distance from the bony portion. Feet, nve-t&amp;gt;xd and 

 webbed. In the fore feet the web extends a short distance beyond the claws, is 

 loose, and falls back when the animal burrows ; claws strong, blunt, the two 

 lateral shorter than the three middle ones. Hind feet short, narrow, turned 

 backwards, and, when the animal is at rest, somewhat resembling a fin. The male 

 ornitliorynchus is armed with a spur on each hind leg, having a canal in it similar 

 to that in the poison fang of venomous serpents, and, like this, also furnished with 

 a gland at the base, secreting a fluid ; hence it has been thought likely, though 

 there is no evidence of the fact, that wounds produced by them would b* 

 dangerous. They have no external ear, and their eyes are very small, but brilliant. 

 The motions of the mandibles in this animal, when seeking its food in the mud and 

 water, are the same as those of a duck when feeding in similar situations. 



The young are produced in a very imperfect state, and ai-e very unlike the full- 

 grown animal. The skin is entirely destitute of fur ; the eyes are not formed, 

 and their place is merely indicated by the presence of a few wrinkles on the skin. 

 The margin of the bill is at that time soft and the tongue advances to its front 

 edge, so that the young animal can obtain nourishment by sucking, which was at 

 first thought impossible. The mammary gland is very simple in structure, and is 

 divided into a large number of separate lobes. The ornithorynchus, when asleep, 

 rolls itself up like a hedgehog, keeping its back warm by bringing over it the 

 flattened tail. It dresses its fur, combing it with its feet, and pecking at it with its 

 beak, and seems to take great delight in keeping it smooth and clean.* 



ORDER VII. PACHYDERMATA. 



429. Why is the seventh order of mammalia called Pachyder- 



Because they are characterised by thick skins or hides. The 

 term is derived from the Greek, and means thick-skinned. 



* Maunder s &quot; Treasury of Natural History.&quot; 

 t Tack-e-dcr-ma -ta. 



